Mechanical fuel pump



Jan. 31, 1961 E. A. JOHNSON ETAL 2,969,745

MECHANICAL FUEL PUMP 2 Sheets-Sheet 1 Filed June 2, 1958 INVENTOR. ELDON A.JOHN SON DONALD R. COMPTON ATTORNEY Jan. 31, 1961 E. A. JOHNSON ETAL MECHANICAL FUEL PUMP 2 Sheets-Sheet 2 Filed June 2. 1958 INVENTOR. ELDON A.JOHN SON DONALD R. COMPTON ATTORNEY United States PatentQ MECHANICAL FUEL PUMP Eldon A. Johnson, St. Louis, Mo., and Donald R. Compton, Belleville, Ill., assignors to ACF Industries, Incorporated, New York, N.Y., a corporation of New Jersey This invention relates to pumps, and more particularly to a diaphragm pump of a type especially suitable for pumping fuel to the carburetor for an internal combustion engine, the diaphragm of the pump being operable by a drive from the engine.

In the manufacture of diaphragm fuel pumps of the class described, it is economically desirable to use for the diaphragm a normally flat relatively thin disk of flexible diaphragm material, as distinguished from a diaphragm molded to have an initial conformation other than flat. In the usual fuel pump design, such a disk has its central portion held between a pair of backing plates and its periphery clamped fiatwise between parts of the pump, with the annular portion of the diaphragm between the backing plates and its clamped periphery in a slack condition to allow for flexing of the diaphragm without any substantial stretching of .the diaphragm. A problem arises in the manufacture of suchipumps 'due to the fact thatthe dispositionof the diaphragm to obtain the slack "tends in some measure undesirably to stress and distort the diaphragm, thereby weakeningit and increasing the difliculty of obtaining a proper seal around its periphery.

In a pump of the class described, with the stated slack in the diaphragm, the volumetric efiiciency and compression ratio of the pump are reduced if theslack is subject to a reversing action-as the diaphragm flexes.

While thistenden'cy may be reduced by making the span between the backing plates and-the clamped margin of the diaphragm relatively small, this decreases thepump capacity. i 'Pumps of the class described are usually made with aspring for driving the diaphragm through its discharge stroke, the diaphragm being returned through its suction stroke by the drive from the engine. As the spring drives the diaphragm through its discharge stroke, the force of the spring decreases. Without compensation for this decrease in the force exerted by the spring, the pressure developed by the diaphragm materially decreases during its discharge stroke. 7

Pumps of the class described have an intake check valve and a discharge check valve, the intake valve opening and the discharge valve closing on a suction stroke of the diaphragm to prime the pumping chamher, the intake valve closing and the discharge valve opening on a discharge stroke of the diaphragm for discharge of fuel from the chamber. It is desirable that the valve arrangement be such as to allow for constructing the pump to have minimum space remaining in the pumping chamber of the pump at the end of a discharge stroke of the diaphrgam, so as not to reduce the compression ratio of the pump. It is also desirable that the valve arrangement be such as to avoid undue disturbance of the fuel in the pumping chamber, particularly in the case where the ratio of vapor to fuel may be relatively high.

In a fuel pump of the class described, the diaphragm is under control of a mechanism including .a rocker arm 2,969,745 Patented lan. 31, 196 1 actuated by an engine-driven cam means in such manner that during part of a cycle of the cam means, the rocker arm is free to allow the diaphragm to be flexed by its operating spring through a discharge stroke, and during another part of the cycle the arm is adapted positively to move the diaphragm through a suction stroke. Heretofore, the mechanism has been such as to cause undesirably noisy slapping, and to require relatively expensive construction for the rocker arm pivot.

Accordingly, it is an object of this invention to provide a diaphragm pump construction of the class described which enables manufacture of pumps using a normally flat disk of flexible material for the diaphragm, without severe bending, stressing and distortion of the diaphragm arising from the provision of slack in the diaphragm. In conjunction with this object are the further objects of providing a construction which, while having a substantial span between the central portion and the clamped margin of the diaphragm, has little tendency to be subject to reverse action of the slack, so as to obtain a relatively high volumetric efliciency and compression ratio, and also providing a construction .which inherently compensates for the decrease in spring force on the diaphragm as it flexes through a discharge stroke so as to tend to maintain the unit pressure developed by the pump more constant throughout the discharge stroke of the diaphragm.

Another object of the invention is the provision of an intake and discharge check valve construction which tends to minimize disturbance of fuel in'the :pumping chamber, and which, while being compact so that it does not seriously reduce the compression'ratio, is reliable in operation for a' relatively long period of time.

indicated in the following claims.

In the accompanying drawings, in which one of various possible embodiments of the invention is illustrated,

Fig. 1 is a vertical section of a pump constructed in accordance with this invention, as it appears apart from an engine with which it may be associated, parts being shown in their position at the end of a discharge stroke;

Fig. 2 is a section corresponding to Fig. 1, showing the pump as it appears when installed with the engine, parts beingshown in their position at the end of a suction stroke;

Fig. 3 is a plan view of a cup-shaped body and valve assembly per se of the pump, parts being broken away;

Fig. 4 is a section taken on line 44 of Fig. 3;

Fig. 5 is a plan view of a discharge valve spring retainer per se;

Fig. 6 is a view in elevation of Fig. 5; and,

Fig. 7 is a right end view of Fig. 1.

Corresponding reference characters indicate corresponding parts throughout the several view of the drawings.

extending from body 3 into a central intake chamber 15 and a surrounding discharge chamber 17. The base 1,?

of receptacle 1 has a central inlet port 21 in which is secured an inlet nipple 23. The peripheral wall 25 of the receptacle has a discharge port 27 in which is fixed a discharge nipple 29. Adjacent the discharge port, the base of the receptacle has a depressed portion providing a sump 31. Body 3 is formed with a circular series-of slots 33 constituting intake valve ports providing for communication from intake chamber 15 to the pumping chamber under control of an intake check valve-35-. The body is also formed with a circular series of slots 37 surrounding slots 33 and constituting discharge valve ports providing for communication from pumping chamher 5 to discharge chamber 17 under control-of adischarge check valve 39.

The casing 11 comprises a conical portion 40 constituting ahousing for the diaphragm 7 and spring 9, and a flaring portion 41 extending laterally from the small end of spring housing-40 constituting a-housing for a rocker arm 43. The diaphragm 7 is fixed on'the lower end of a stem 45 which extends slidably through a packingmember- 47 held in theupper end of spring housing 40. Spring 9 surrounds stem 45, reacting from a gland 48 hearing against packingmember 47. Stem 45 extends up into the inner end of rocker arm housing 41 through an opening 49. i The rocker arm 43 has longitudinal ribs 51 receiving s q-area a pivot pin 52. The ends. of this pin are mounted in grooves 53 cast in the sides of the rocker arm housing 41. These grooves are initially of uniform'width throughout their length, as indicated by the dotted lines 53a in Fig. 2, extending inward from the open outer end of hous ing 41. After-the pin52 'withth'e rockerarm thereon has been inserted inthe l'grooves; portions of the sides-of housing 41 arepeenedainward' toward'the grooves -and against-the: pin as;.;indicated at 54 to hold the pin 'in place. Therockerarm has "a slot 55 extending outward from its inner end receiving thestem 415. The-'l'atter has a' head 57 at-its upper end engageable by the rocker arm.

The outer end of therocker arm is downwardly curved as indicated at 58. A leaf spring-59 has-one end secured as by a rivet 60.to the rocker arm 43 at a point spaced from the curvedouter end 58 of the arm, preferably at a point between pin 52 and the inner end of the arm; The spring 59, extends toward the outer endof the rockerarm; It has a downwardly curved freeend portion 62-whichis normally spacedfrorn the outer end portion 58'of the arm. When the pump isinstalled on an engine, theffre'e end. portion 62 ofthe spring is engaged by an engine driven push rod 61 which is angled downward in thedirection toward the pump. It will be understood that this push rod is actuated byan engine driven cam '(not shown). The-action of the cam and push rod are such that-during a part of the cycle of the cam, the push rod is movable back to a retractedposition in which the rockor arm 43 is freed to rock counterclockwise from the retracted position in which'it isshown in Fig. 2 to the advanced position in which it is shown in Fig. 1. With the rocker arm freed for such movement, the stem 45 is freed to enable spring 9 to drive the diaphragm 7 down through a discharge stroke if fuel is free to How out of pumping chamber 5 and discharge chamber 17 (as-determined by the requirements of a carburetor supplied by the pump).

When, therocker arm rocks counterclockwise from its retracted position of Fig. 2, leaf spring 59 remains in engagement with the end of the push rod 61, flexing in the direction toward the rocker arm. During another part of the cycle, the push rod 61 is moved in the; direction toward the rocker arm.- If, prior-to such movement; the rocker arm hasbeen movedby stem 45 to the Figil advanced position, the push rod acts through the leaf spring 59 to drive the" rocker arm back to the Fig. 2retracted position, thereby pulling up the stem 45 and driving the diaphragm up through a suction stroke. With the leaf spring interposed between the push rod 6l and the rocker arm, noisy slapping is eliminated. Also, with the push rod acting on the rocker arm via leaf spring 59 at an angle as shown, the arm is constantly biased in inward direction as regards rocker arm housin 41, whereby pivot pin 52 is constantly biased against the inner ends of grooves 53. This makes possible the use of the relatively simple and inexpensive mode of holding the pin 52 in place in the pre-cast grooves 53 by-peening at 54.

The peripheral wall 25 ofreceptacle 1 is formed with a conical flaring shoulder 63, and, above that, with-a cylindrical portion 65 ha ving" aninside diameter slightly larger than the diameter of the rim of cup-shaped body 3. The base of body 3- is designated67 and its peripheral wall is designated 69. The interior surface 71 of the latter is of conical fo'rm, flaring outward away from base 67, the angle of flare being for example. The wall 69 has an external annular rib 73 which seats on the conical shoulder 63 of the receptacle. Above the rib 73' there is a packing ring 77 compressed between wall 69' and shoulder 63 for sealing the receptacle. The base 67 ot body 3 has a shallow circular recess 79 on the inside away from the receptacle, anda centralcupshaped'olfset SI-projecting outward from base 67 and down into the receptacle providing a. recess 83 con$tituting" an intake valve chamber. Theannular partition or projection-13zis constituted by an integral extension of? offset 81- which is of smaller diameter than offset 81 to'providean annular shoulderconstituting a discharge valve seat 85 surrounding the inner end ofv partition 13. The latter'extends down to the, base .12 of the receptacle 1, a gasket 87 being-interposed between the endrot partition .1-3pand base 19 surrounding-theinner end of intake nipple; 23. Base 8.9. of, ofiset- 8.1; has-a1 central oni a 110831311. projeeting down within partition. T e. ntak valve; ports 1: 33- extend; through theybasez'iil o Qfis surroundingpartition 13 providing-air domes 95 and 9.7.

The inside face'99of the base '89 of cup'shaped ofiset 8.1 c nstit es valve atforgthein ake heck: a ve 35,- Pre erab y. h a e: or. s t. 99. is;.slish v cbacavc b ing: ormed: with ayslisht taper (a aper, for, ex.-

ampl laring up,towardiutalsev-alve sh aths; 83.- Thi taper is exaggerated in Fig. 4. At the centerotbase 82otcfi 81 sa tlfll, e t nd-i g; w i to boss 91.. Th d sch rge ve. seat isprcie b y iareuate oi aur, being; termed; so hat. t sur ace define here y s ab ion f a y indric l sur ce of r a i e y long: adiu gene at d b ut n x s. yin f ns e able dis nc be ow t e t 8 ext i s at right a es t t e. xis q n y ,3. The rcua e n o catSS is exaggerat in Fig.

The diaphragm 5 consists of a relatviely thin diskof flexible fuel-resistant material, such as a suitable synthetic rubber with a fabric-insert which, in its initial unstres e c di ion, s. fl (or at e s s t nti y The diaphragm mounted at the end ofstem 45. between, a pair of circular backing plates and 107. Plate 105 engages the face of the diaphragm toward. the base 67 of body 3, and plate,107 engages the other face of the, diaphragm. Plate105 is relatively thick as comparedwith plate 107 andis of somewhat ma er. iam e han e s, 79 ofit r in as sh n nFia T ed e tpl te 0 at slif cc hi h. 11- gases he. d ph m; is; unde as. n i at d. at, .09.- Plate 1 7. hi h. may f rmed otshe me l, has. a nane; corrugation or rib 111 projecting away from the iap ragm and, f in a eat o nfin ng he l e end of spring 9. Plate 107 is oflargerdiameter than plate 105, and the margin of plate 107 which overhangs plate 105 is flared outward in downward direction to provide a rim '113 on plate 107 constraining the dia= phra'gm to have a-portion originally flaring outward in downward direction from the plates 105 and 107 toward the base of the body 3.

In assembling the pump, after the check valves have been assembled with body 3 in a manner to be described, the body 3 is dropped into the receptacle 1, the upper cylindric portion 65 of the receptacle 1 being completely open at this stage of operations, with packing ring 77 interposed between wall 69 of body 3 and the flaring shoulder 63 of the receptacle. Then, the diaphragm is assembled with the body 3 simply by inserting it in the body in the manner apparent from Fig. 1, in which the flaring portion of the diaphragm lying outward of the rim'113 of plate 107 engages the conical internal surface 71 of wall 69 of body 3, flaring upward and outward to the rim of the body. Laying the diaphragm in body 3 in this manner is readily accomplished without undue bending, distortion or wrinkling of the diaphragm. Then the lower end of the housing 40 is entered in the upper cylindric portion 65 of the receptacle, with rim 115 on housing 40 engaging the marginal portion 116 of' the diaphragm. Rim 115 is preferably formed with a beveled edge 117 conforming to the taper of surface 71 for engaging the marginal portion 116 of the diaphragm, and projects outward to provide an annular shoulder 119. After housing 40 is in place, the upper part of cylindric portion 65 of the receptacle is crimped.

over on shoulder 119 to form an inwardly directed rim 121 holding the parts in assembly, with suflicient pressure on the marginal portion 116 of the diaphragm and on packing ring 77 to seal the receptacle 1 and the pump? iug chamber 5. Portion 116 being of conical form rather than fiat, pressure is applied over a relatively extensive area adjacent the periphery of the diaphragm for a good seal.

Rim 113 of plate 107 constitutes. means constraining the diaphragm to have a portion flaring outward in the direction toward the base of body 3. This portion of the diaphragm merges into the clamped marginal portion 116 of the diaphragm in the form of a single annular free non-reversing loop 120 convex toward the base of body 3 (the bottom of the pumping chamber 5). The clamped marginal portion 116 of the diaphragm flares outward away from the base of body 3 in facewise engagement with an outer portion of the flaring internal surface 71 of body 3 and conforms in shape to surface -71. When the diaphragm is in its retracted position of Fig. 2, spaced from the bottom of pumpingchamber 5, the effective diameter and area of the diaphragm are a maximum. As the diaphragm flexes down through a discharge stroke, the loop 120 rolls into engagement with the flaring internal surface 71 of body 3, whereby the effective diameter and area of the diaphragm decrease to a minimum (compare Fig. 2 and Fig. 1). At the end of the discharge stroke of the diaphragm, the loop is in effect flattened out completely against the internal surface 71 of wall 69 of body 3, and plate 105 engages the bottom of body 3 in recess 79 so that there is practically no space remaining in chamber 5.

The angle of flare of surface 71 is so related to the I rate of the spring 9 that, as the diaphragm advances through a discharge stroke, its effective area diminishes substantially proportionally to the decrease in the force exerted by the spring 9, thereby maintaining the unit pressure developed by the diaphragm substantially constant throughout its discharge stroke. For example, in a typical embodiment of the invention, when the diaphragm is in retracted position, its effective diameter is 3.230 inches, its effective area is 8.19 square inches, and spring 9 is compressed to a length of 1.000 inch and exerts a total force of 45.5 lbs. on the diaphragm. Accordingly, at the start of a discharge stroke, the diaphragm develops 5.5 psi. unit pressure (45.5 divided by 8.19). Spring9 expands to a length of 1.350 inches in driving the diaphragm to the end of a discharge stroke. With the 45 flare for surface 71, the efiective diameter of the diaphragm decreases to 2.835 inches, its effective area thereby decreases to 6.31 square inches. The force exerted by the spring decreases to 32.2 lbs. Accordingly, the unit pressure developed by the diaphragm at the end of its discharge stroke is 5.1 psi. (32.2 divided by 6.31).

The intake check valve 35 compirses a normally flat thin disk of flexible resilient fuel-resistant material, such as a suitable synthetic rubber with a fabric insert. This disk is of such diameter as to overlie the intake valve ports 33, but of smaller diameter than the circular series of discharge valve ports 37 so as not to obstruct the latter. Backing the valve 35 is a thin generally flat sheet metal spring in the form of a spider having a central hub portion 127, radial spring arms-129, and arcuate fingers 131 at the ends ofthearms ,(see Fig. 3). ,Spring 125 is. backed by a retainer 133 constituted by a sheet metal stamping comprising a circular plate 'or head 135 and a stem.137 struck from the 'head. Stern 137 is pressed in the socket 101 and extends through central openings in the hub ofthe spring 125 and valve 35. Head 135 is spaced from seat 99, being located at the top of intake valve chamber 83. Tongues 139 are struck from the head 135 and engage the spring 125 at low points of the concavity of seat 99 tohold it down. The construction is preferably such that, after assembly, tongues 139 have little if anyspring action, acting without appreciable yielding to hold the spring 125 inplace.

The discharge check valve 39 ,comprises a thin normally flat ring of flexible fuel-resistant material, such as a-suitable synthetic rubber-with a fabric insert, surrounding the partition 13 and engaging, the seat 85.. Backing the ring-shaped'valve 39 is a thin normally flat sheet metal ring 141 which-constitutes a valve spring, This is backed by a retainer '143c'ornprising' a. flat sheet metal ring 145 having axially extending tongues 147 pressfitted in grooves 149 on the exterior of partition 13, and struck-out arcuate arms 151 engaging spring ring 141 at low points of the concavity of seat 85 tohold it against the valve 39. The construction is preferably such that arms 151 have little if any spring action, acting without appreciable yielding to hold spring 141 in place.

Operation is as follows:

With the pumping chamber 5 primed with fuel, and with fuel trapped in the discharge chamber 17 and the line (not shown) leading to the carburetor, the operation of push. rod 61 simply results in relatively quiet flexure of leaf spring 59 without any action of rocker arm 43,. The fuel trapped in chamber 5 maintains the diaphragm 7 in its retracted position of Fig. 2 against the bias of spring 9 during return (upward) strokes of rod 61. Upon a demand from the carburetor for fuel, fuel is free to flow out of receptacle 1 and spring 9 thereupon acts during a return stroke of rod 61 to drive the diaphragm down from the Fig. 2 position through a discharge stroke to the Fig.- 1 position. Rocker arm 43 is freed to rock counterclockwise from its Fig. 2 position to permit stem 45 to move downward during the return stroke of rod 61. As the diaphragm moves down, the intake check valve 35 is held closed against its seat 99 and the discharge check valve 39 flexes open against the closing bias of spring ring 141.

As the diaphragm 7 is driven down, loop .120 rolls onto the flaring internal surface 71 of the cup-shaped pump body 3. As previously explained, this rolling action results in decrease of the effective working area of the diaphragm throughout the. discharge stroke substantially in proportion to the decrease in the force exerted by spring 9 as it expands-whereby the unit pressuredeveloped by the diaphragm is maintained substantiallyconstant, the pressure at the end of the discharge stroke being nearly that. at the beginning of the. discharge stroke. Since the outer margin 116 of loop 120 is clamped in such manner as toflare up and out and its inner margin s ams is constrained by rim 113 of 'pl'ate 107 to flare down and out, loop 120 is positively set or directed to remain' convex toward the bottom of the pumping chamber without reversal as the diaphragm moves, even though the span between rim 113 and. margin116 is relatively'lar'ge. In the advanced Fig. 1 position of the diaphragm, the loop 120 is in engagement with surface 71' to the base of body 3, and plate 105 substantially fills'recess 79 so that there is little space left in chamber 51. "Accordingly, the volumetric efliciency and compression ratio of the pump are relatively high.

' Upon any forward (downward) strolte ofrod 61 fol lowing a i a ge troke ff h 'diap m; the h? arm 43 is rocked clockwisje froin itjsfFig. 1 position back to its Fig. 2 position, andfptills 'up'stern 45 to drawthe diaphragm through a suctionfstrolce against the bias of spring 9. The intake check 'valge 35 flaxes open against the closing bias of spring 125 and aid is drawn into the pumping chamber 5 through; intake'ports33 from intake chamber 15, The dischargec heck valve 39 is held closed against its seat 85. With fuel enteringithe pumping cham} ber via ports 33 on asuction stroke of thediaphragm, and being discharged via ports 37 closely surrounding ports 33 on a discharge stroke, a flow of fuel'laterally across the pumping chamber 5 is minimizedfthereby minimizing fuel disturbancejin the pumping chamber. It will also be 'observed'that the valvearrangement issuch that there is a minimum of claara'ncel in the; pumping chamber at nd o a, di charge troke. at he. iaph a m, e

"The intake check valve flf maybecut out of the center ofjthe same piece of material as the discharge I3 J nd 5 ,r'riaib t 1 Q thesame piece of sheet, metal as the spring "141, thereby avoiding waste of material. 'Use of the flat check valve members 35' and 39 andflat springs 125 and 141' inconjunction with'the spring retainers 133 and 143 provides a construction which is compact and reliable in operation for a relativelylong period of time. In this respect, it will be noted that the springs 125 and 141 hold the valve members 35 and"39 in slightly arched condition against their concave seats, and this tends to, maintain the valve members in condition to provide a good. seal. In view of theiabove, it will be seen th at the several objects of the invention are achieved and other advana tageous results obtained; As various changes could be made in the above constructions without departingfrom the scope of" the invenf tion, it is'intended that allmatter'contained in the above description or shown'in the accompanying drawings shall be interpreted asjillustrative and not in a lirrritin'g'sense. Weclaim: 1 In a diaphragm pump, a cup-shaped body having a base and a peripheral wall defining a pumping chamber, the internal surface of the peripheral wall of said body flaring outward away from the base, a flexible diaphragm, said diaphragm closing the pumping chamber and having a marginal portion flaring outward away from the base in facewise engagement with an outer portion of said flaring internal surface and conforming in shape thereto, a housing enclosing the diaphragm and engaging said flaring marginal portion ofthe 'diaphragm and clamping it in sealed relation against said outer portion of the flaring internal surface, means engaging a central portion ofthe' diaphragm holding said central portion substantially flat, said' means including a rim constraining thediaphragm to have a portion flaring outward in thedirec-tion towardthebasejof'the body and merging intosaid marginal portion ofthe diaphragm intheform of a 'free loop, anda sp'riiifg' in said housing reacting from the hou'singagainst said constraining means and biasing the diaphragm in the direction toward the baseofsaid. body,

2. Ina diaphragm pump, a cup-shaped body having a base and a peripheral wall defining a pumping chain, her, the internal surface of the peripheral wall of said body flaring outward away from the base, a flexible diaphragm, said diaphragm closing the pumping chamber and having a marginal portion flaring outward away from the base in facewise engagement with an outer portion of said flaring internal surface and conforming in shape thereto, a housing enclosing the diaphragm and engaging said flaring marginal portion of the dia phragm and clamping it in sealed relation against said outer portion of the flaring internal surface, and a coinpres-sion spring in said housing biasing the diaphragm in the direction toward the base of the body, means to move said diaphragm to a retracted position spaced from the base of the body to compress said spring, said spring acting with decreasing force to move said diaphragm to an advanced position at the base wherein the diaphragm engages said flaring internal surface from said clamped marginal portion of the diaphragm substantially to the base, the flare of said internal surface being so related to the rate of the spring that, as the diaphragm advances, its efiective working area diminishes substantially proportionally to the decrease in the force exerted by the spring to thereby discharge fuel from the pumpingc'hamber under substantially constant pressure.

3. In a diaphragm pump, a cup-shaped body having a base and a peripheral wall defining a pumping chamhertthe'internal surface of the peripheral wall of said body flaringbu'tw'ard away from the base, a flexible diaphragr'msaid diaphragm closing the pumping chamber and having amarginal portion flaring outward, away from; the base in facewise engagement with an outer portion of saidv flaring internal surface and conforming in shapeth'ereto, a housing enclosing the diaphragm and engag ng said flaring marginal portion of the diaphragm and clamping it in sealed relation against said outer" portion of the flaring internal surface, means. engaging a central portion of the diaphragm holding said central portion substantially flat and constraining the diaphragm to have a portion flaring outward in the direction toward the base of the body and merging into said marginal portion of the diaphragm in the form of -a free loop, and a compression spring in said housing reacting. from the housing against said constraining means.

and biasing, the diaphragm in the direction toward the baseof the body, means to move said diaphragm to a retracted position spaced from the base. ofthe body. to compresssaid spring, said spring acting with decreasing force to move said diaphragm to an advanced position at the base wherein said loop engages said flaring internal surface from said clamped marginal portion of the diaphragm substantially to the base, said loop rolling onto said flaring internal surface and thereby diminishing the efiective working area of the diaphragm as the diaphragm advances, the flare of said internal surface being so related to the rate of the spring that, as the diaphragm advances, its effective working area diminishes substantially proportionally to the decrease in the force exerted by the spring.

4. In a diaphragm pump, a cup-shaped receptacle having a base and a peripheral wall, a cup-shaped body having a baseand a peripheral wall defininga. pumping chamber, said body beingmounted in position closing the receptacle with the, base of the body toward the base of the receptacle, the internal surface of the peripheral wall of .said body flaring outward away from the base, a flexible diaphragm which, when unstressed, is ,sribstantiallyflat, said diaphragmv closing thev pumping chamber and having a marginal portion flaringoutward away from the base of the body in facewise engagement with an outer portion of said flaring internal surface and conforming in shape thereto, means holding said flaring marginal portion of the diaphragm against. said outer portion ofthe flaring internal surface, said body having a tubular projection extending to the base of the sesame receptacle constituting an annular partition dividing the receptacle into an intake chamber within the partition and a surrounding discharge chamber, the base of the receptacle having an inlet to the intake chamber and the receptacle having an outlet from the discharge chamber, the base of the body having an intake port providing for communication from the intake chamber to the pumping chamber and a discharge port providing for communication from the pumping chamber to the discharge chamber, an intake check valve mounted on the side of the base of the body remote from the base of the receptacle for closing the intake port on a discharge stroke of the diaphragm, and a discharge check valve on the receptacle side of the base of the body for closing the discharge port on a suction stroke of the diaphragm.

5. In a diaphragm pump, a cup-shaped sheet metal receptacle having a base and a peripheral wall provided with a shoulder, a cup-shaped body having a base and a peripheral wall defining a pumping chamber, said body being mounted in the receptacle on the shoulder with the base of the body toward the base of the receptacle, a flexible diaphragm closing the pumping chamber, means for clamping a marginal portion of the diaphragm against the body, said receptacle having an inwardly directed rim engaging over said clamping means, said body having an integral tubular projection extending to the base of the receptacle constituting an annular partition dividing the receptacle into an intake chamber and a discharge chamber, the receptacle having an inlet to the intake chamber and an outlet from the discharge chamber, the base of the body having an intake port providing for communication from the intake chamber to the pumping chamber and a discharge port providing for communication from the pumping chamber to the discharge chamber, an intake check valve on the pumping chamber side of the base of the body remote from the base of said receptacle for closing the intake port on a discharge stroke of the diaphragm, and a discharge check valve on the receptacle side of the base of the body for closing the discharge port on a suction stroke of the diaphragm.

6. In a diaphragm pump, a cup-shaped sheet metal receptacle having a base and a peripheral wall provided with a shoulder, a cup-shaped body having a base and a peripheral wall defining a pumping chamber, said body being mounted in the receptacle on the shoulder with the base of the body toward the base of the receptacle, a flexible diaphragm closing the pumping chamber, means for clamping a marginal portion of the diaphragm against the body, said receptacle having an inwardly directed rim engaging over said clamping means, a partition in said receptacle dividing the receptacle into an intake chamber and a discharge chamber, the receptacle having an inlet to the intake chamber and an outlet from the discharge chamber, the body having an intake port providing for communication from the intake chamher to the pumping chamber and a discharge port providing for communication from the pumping chamber to the discharge chamber, an intake check valve associated with the intake port for closing the intake port on a discharge stroke of the diaparagm, and a discharge check valve associated with the discharge port for closing the discharge port on a suction stroke of the diaphragm said intake and discharge check valves being mounted on opposite sides of the base of said body, the base of said body having a recess in communication with said intake and discharge ports, and said intake check valve being mounted within said recess.

7. In a diaphragm pump, a cup-shaped receptacle having a base and a peripheral wall, a cup-shaped body having a base and a peripheral wall defining a pumping chamber, said body being mounted in position closing the receptacle with the base of the body toward the base of the receptacle, a flexible diaphragm closing the pumping chamber, means holding 'a' marginal portion of the diaphragm against the body, an annular partition extending between the base of the body and the base of the receptacle dividing the receptacle into an intake chamber within the partition and a surrounding discharge chamber, the base of the receptacle having an inlet to the intake chamber and the receptacle having an outlet from the discharge chamber, the base of the body having a series of intake ports around the axis of the partition providing for communication from the intake chamber to the pumping chamber and a series of discharge ports surrounding the series of intake ports and located outward of the partition providing for communication from the pumping chamber to the discharge chamber, an intake check valve constituted by a generally fiat flexible valve member engageable with the pump ing chamber side of the base of the body remote from the base of the receptacle for closing the intake ports on a discharge stroke of the diaphragm, and a discharge check valve constituted by a substantially flat flexible ring valve member surrounding the partition and engageable with the receptacle side of the base of the body for closing the discharge ports on a suction'stroke of the diaphragm.

8. In a diaphragm pump as set forth in claim 7, said intake check valve comprising a generally flat spring member engaging the back side of said intake valve member, and a retainer having a portion fixed in the base of the body and extending through the intake check valve member and said spring member, said retainer engaging said spring member and having a portion overlying said spring member to limit movement of said spring member away from the base of said body.

9. In a diaphragm pump as set forth in claim 8, the base of the body having a recess defining an intake valve chamber, said intake check valve member, spring member, and retainer being located in said recess.

10. In a diaphragm pump as set forth in claim 7, said discharge check valve comprising a generally flat spring ring member engaging the back side of said discharge valve member, and a discharge valve retainer mounted on the annular partition and engaging said discharge spring ring member.

11. In a diaphragm pump as set forth in claim 7, the base of the body having a recess defining an intake valve chamber, the bottom of the recess constituting a seat for the intake check valve member, the intake check valve member being located in said recess engaging said seat, a generally flat spring member in the recess backing the intake check valve member, a retainer in the recess backing the spring member, said retainer having a stem extending through the spring member and intake check valve member fixed in the base of the body at the bottom of the recess, a head on the stem overlying the spring member, and fingers on the head engaging the spring member, a portion of the base of the body surrounding the partition constituting a seat for the discharge check valve member, a generally flat spring ring member surrounding the partition backing said discharge check valve member, and a retainer for said flat spring ring member comprising a ring fixed on the partition having fingers engaging the flat spring ring member.

1 In a diaphragm pump as set forth in claim 11, said seats being of concave form, and said fingers holding the spring members against low regions of the concavities.

13. In a diaphragm pump, means defining a pumping chamber, a diaphragm closing the pumping chamber, a stem connected to said diaphragm, a spring for moving the diaphragm through a discharge stroke, means com prising a rocker arm having one end thereof engageable with said stem for moving the diaphragm through a suction stroke, and a leaf spring secured at one end to the medial portion of the rocker arm and extending longitudinally toward the other end of the rocker arm and 1 I normally having its free end spaced from the rocker arm for engagement by an engine driven element.

14. In a diaphragm pump, means defining a pumping chamber, a diaphragm closing the pumping chamber, a housing enclosing the diaphragm, a rocker arm housing extending-laterally from the diaphragm housing, a spring in the diaphragm housing biasing the diaphragm in discharge. direction, a stem extendingfrom the diaphragm into the inner end of the. rocker arm. housing having a head at its outer end, said rocker arm housing being open at its outer end, a rocker arm pivoted in and extending longitudinally of said rocker arm housing, said arm having a connection at its inner end. with said stem, and a leaf spring secured at one end thereofto the rocker arm at a point spaced from itsrouter end and extending toward said outer end and normally having its dree. end spaced from the rocker arm for engagement by an engine. driven element.

15.. In a diaphragm pump, means defining a pumping chamber, a diaphragm closing the pumping chamber, a housing enclosing the. diaphragm, a rocker arm housing extending laterally from the diaphragm housing, a spring in, the diaphragm housing biasing the diaphragm in discharge direction, a stem extending from the diaphragm into the inner end of the rocker arm housing having a head at its outer end, said rocker arm housing being open at its, outer end and having grooves and peened portions at. the sides thereof on the interior, a. pivot pin having its, ends received in said grooves and. held therein by said peened portions on the sides of the rocker arm housing, a rocker arm carried by the pin extending longitudinally in said housing, said arm having a slot extending outward from its inner and receiving said stem, and a leaf spring secured to the rocker arm at a point spaced from its, outer end and extending toward the outer end oi the rocker arm and normally having its free end spaced, from the. rocker arm.

References Cited in the file of this patent. UNITED STATES PATENTS 10,428 Hitchcock Jan. 17, 1854 953,945 Falk Apr. 5, 1910 2,576,894 Van Ranst et a1. Nov. 27, 1951 2,638,849 Budlane May 19, 1953 2,801,594 Lewis Aug. 6, 1957 

